My general algorithm is : Q: is this problem likely to appear on HN? If YES then no need to submit radar report; if NO then problem affected user base too small to escalate radar report thus no point wasting time with submitting a radar report.

In fairness, this applies to any large company. What gets the grease is volume field reports from Customer Support, not bug reports from developers, no matter the level of detail.

I have an outstanding Radar report of a problem with the Fusion drive from at least Yosemite on; on a full SSD in the CoreStorage volume, allocating a file buffer larger than the 4GB copy partition will instantly hang the file system, effectively disabling the computer. You can't even reboot, hard power cycle is the only solution. This isn't in general a good way to create a file, but Transmission does exactly this, unfortunately.